Method of insulating panels



Patented Nov. i141, 1939 UNHTED STAT greases FHQE METHOD or msma'rmoPANELS No Drawing. Application November 30, 1935, Serial No. 52,3415.Renewed April 12, 1939 2 Claims.

This invention relates to waterproof adhesive compounds and to methodsof manufacturing same and is concerned more particularly with adhesivecompositions of an asphaltic or similar 5 bituminous character, or of arubber character.

The invention is more particularly concerned with adhesive compounds ofthe aforesaid character which can be successfully employed underconditions which have heretofore presented considerable difliculty'inthe attainment of the desired adhesive effect.

One example of the particular conditions under which the adhesivecompounds made in accordance with my invention may be successfullyemployed are those which prevail in the application of sound deadeningsheets or pads to the metal parts of vehicle bodies during the course ofmanufacture of the vehicle.

Various forms and types of sound insulating 0' sheets or pads have beenemployed in the auto motive industry for deadening the sound of thevibrating metal parts of car bodies, the sound deadening sheet or padbeing attached, for this purpose, to the inner surface of the metalparts, the

vibrations of which it is desired to dampen. Thus, forexample, sheets orpads of relatively heavy porous or bibulous unsaturated felts, have beenused for deadening the vibrational sounds of metal parts of car bodies.Sound insulating material of this character has been successfullyafiixed to the metal parts by the employment of bituminous emulsions ofthose types in which a mineral colloid constitutes the dispersing agent.It is essen tial, in the use of an aqueous emulsion of bitumen or thelike, for the purpose of affixing the sound deadening layer to the metallayer, that the emulsion be of a. character such that when the water ofthe emulsion has been removed, the resultant adhesive film will not flowat temperato tures considerably in excess of the melting point of thebitumen contained in the emulsion. This requirement of the adhesive ismade necessary by reason of the fact that in the application of thesound deadening material to the metal parts of t5 the body, the adhesivemust be able to withstand flow at the temperatures of the ovens throughwhich the body of the car with the sound insulating material afiixedthereto must pass, as otherwise the layer of the sound insulatingmaterial will slide off or be otherwise parted from the metal layer towhich it is intended to adhere. Furthermore, the requirement that thefilm shall resistjfiow at temperatures considerably above the meltingpoint of the bitumen contained in the emulsion, is also essential inorder that the insulating material remain in place and not movesubstantially from its fixed position upon the metal layer under theheat of summer temperatures to which automobiles are subjected in use.

Bituminous emulsions of the aforesaid char- 5 acter which haveheretofore been successfully 7 used for said purpose, and possessing thecharacteristics just mentioned, are those made with the use of bentoniteor bentonite-like materials as the dispersing agent in accordance, forex- 10 ample, with Kirsohbraun Patent No. 1,620,899.

While emulsions of this type have, as stated, been successfully used forcementing unsaturated sheets or pads of fibrous felt to metal bodyparts,

' recent developments in the automotive industry have made it necessaryto employ more or less waterproofedsound deadening materials, such asfelts saturated to various degrees of waterproofness with asphalt, orthe like.

In the use of these more or less waterproofed types of sound deadeningmaterials, however, considerable dificulty has been encountered insuccessfully cementing the same with bituminous emulsions of thecharacter above described, to the metal parts of the body, under theconditions which necessarily prevail when this operation of aflixing thesound deadening material to the metal parts must be performed. In fact,in certain instances, the attempt to cement the more or less waterprooftype of sound deadening material to the metal parts of the body have metwith complete failure.

An object of the invention is to provide an improved form of compositionfor successfully cementing these types of materials to the metal partsof a body.

Another object of the invention is to provide an adhesive composition ofthe character indicated which will at the same time possess the charac--teristic of resistance to flow under high heats which is obtained, asabove stated, with the use of bituminous emulsions made with bentoniteor similar mineral colloids as the dispersing agent.

In approaching this problem, I found that the reason that bituminousemulsions of the character described may be successfully used as acementing medium for unsaturated sound-deadening felts, whereas they aretroublesome and in many instances completely unsatisfactory where a moreor less waterproof sound-deadening material such as saturated felt isused, is that in the former case the porous or bibulous character of theunsaturated felt is so comparatively great as to enable a suflicientportion of the water con-' tent of the emulsion to escape through thelayer of sound deadening material itself before encounteringtemperatures sumciently high to convert water into steam in the oventhrough which the body with the attached layer of sound insulatingmaterial must pass in course of construction. Hence before encounteringthe waterboiling temperature, the emulsion, in the first case, has ampleopportunity to undergo sumcient inversion or a sufiicient coalescence ofthe bituminous particles to render the film thereof adequately adhesiveand thereby prevent any steam that may be formed from blowing orotherwise forcing the layer of insulating material away from the metallayer. On the other hand, where the insulating layer consists of more orless waterproofed material, a sufficient amount of water to cause thefilm of emulsion to invert and take on an adhesive condition cannotescape before temperatures sufiiciently high to convert water into steamare reached in the passage of the united materials through the ovens;and consequently, at that stage, there is a lack of sufficient adhesionbetween the insulating layer and the metal layer, and the remainingwater entrapped between the two layers results in a blowing off orforcing away of the layer of insulating material from the metal layerwhen temperatures of the order of 212 F. are reached. In this connectionit may be noted that bituminous emulsions such as those made inaccordance with the aforesaid Kirschbraun patent, and which provide awater-free film capable of resisting flow under high heats, require thatapproximately 93 to 98% of the water content of the emulsion be removedbefore the dispersed bitumen particles can coalesce and cause the filmto function as an adhesive. Also it may be stated that the drying ovensthrough which car bodies are passed during the course of construction ofautomobiles normally reach a temperature of from 220 to 280 F. and thatthe bodies remain in these drying ovens anywhere from one-fourth of anhour to as much as three hours.

The adhesive compositions made in accordance with my invention I havefound to be eminently satisfacory as a medium for cementing more or lesswaterproof insulating materials to the metal parts of car bodies underany of the'aforesaid conditions of temperature and time of drying towhich they may be subjected during the construction thereof.

Stated generally, and without intending to limit the scope of theinvention; the adhesive compositions made in accordance with myinvention consist essentially of an emulsion of waterproof material suchas asphalt, in water, the emulsion be ing of that character which willproduce a film capable of resisting fiow under temperatures greatly inexcess of the melting point of the asphalt, together with a materialwhich will so act upon the emulsion system as to cause a film thereof toinvert and the particles of dispersed tion when only as little as 20%,and in any case when considerably less than 90% of the water contentthereof has been eliminated, although this depends to some extent uponthe rate at l which the temperature of the film is increased.

The film of the composition thus rapi ly er s 3,

strong adhesive function due to the fact that the oily character of thesurface of felt saturated with asphalt or the like is readily Wetted bythe composition which is itself also of an oily character. This is inmarked distinction to the action of films of bituminous emulsion asordinarily produced. This distinction can readily be observed by lightlypressing a pad of saturated felt into a film of the ordinary type ofbituminous emulsions of the character herein set forth, applied to alayer of metal, and then removing the pad from the metal layer. The padwill show only water on the surface thereof thus indicating that thefilm of the emulsion has not wetted the surface of the pad with anythingmore than water. On the other hand, when a similar test is applied tothe compositions made in accordance with my invention, the removal ofthe pad from the metal layer will show that the parting takes placethrough the film of the bituminous portion of the composition, hasselectively wetted the pad and adhered not only to the surface of themetal, but to the surface of the removal pad as well.

As one illustration of an embodiment of the invention in a compositionwhich meets the requirements hereinbefore set forth, the followingformula may be given:

Asphalt (51 to 60 penetration) 56 Water M 39 Bentonite (as dispersingagent) 2 Kerosene 3 oxalic acid 0.02 Amyl acetate 0.05

In the composition as represented by the above formula, the keroseneconstitutes the activating agent which causes the emulsion to invert andthe dispersed particles of the bitumen to coalesce while the film of thecomposition still contains substantial amounts of water, this actiontaking place in many instances when as much as 90% of the original watercontent of the emulsion is still present, although as heretofore stated,this may vary with the rate at which the water is driven off. Thekerosene may be employed in quantities varying from 3 to 10% by weightof the finished product. Essentially, however, the activating agentmust, in order to attain the objects of the invention, be of a characterand be employed in quantities sufiicient to cause the film of theemulsion to take on a condition of inversion or sufiicient adhesivecapacity to enable it to hold material such as saturated felt to themetal surface to which it is applied, without blowing off, during theconversion of the remaining portions of the water in the film into steamwhen Water boiling temperatures are reached in the drying process.

In lieu of the kerosene as the activating agent specifically set forthin the above formula, other materials may be employed to function in theway in which the kerosene does. Thus for ex ample, 'the activating agentmay consist of relatively small amounts of a solution of rubber in asolvent, or of a solution of certain gums and/or resins in a solvent;and in general, any other substance which will not materially change thefluid character of the emulsion but will cause it to invert to theadhesive character specified, in the presence of a 'much higher watercontent than if the activating substance is omitted.

The purpose of the oxalic acid in the formula above given is to lowerand retain a lowered viscosity of the emulsion, while keeping it atsubstantially the same water content with which the Parts pugmillingaction and the oxalic acid both serve emulsion is initially produced,(i. e., without requiring large additional quantities of water for thethinning), and thereby to facilitate the incorporation of the keroseneor other activating agent into the emulsion. Substances other thanoxalic acid, well known in the art for this purpose, may be employed inlieu of the oxalic acid. to retain the liquid character of the product;or this effect may be induced in other ways known to the art.

The amyl acetate in the formula above given serves merely as a deodorantto disguise or obliterate the odor of the kerosene.

In the manufacture of the adhesive compositions in accordance with myinvention, as typified by the above stated formula, I prefer to proceedby first making a base emulsion of the asphalt or other waterproofmaterial in water with the aid of the bentonite or other emulsifyingagent suitable for the purpose, having in mind particularly therequirement that the water-free film of the emulsion must be capable ofresisting flow at temperatures greatly in excess of the melting point ofthe dispersed material. thus produced in accordance with commercialpractice in the art and containing approximately 37% water, 60% asphaltand 2 to 3% bentonite, is one in which the particle size of thedispersed asphalt averages about 18 microns, The emulsifying temperaturefor the production of the base emulsion will range from approximately130 to 140 F. for asphalt of about the penetration inkiicated.

The base emulsion as discharged from the emulsifying apparatus is thenpreferably cooled from the emulsifying temperature of 130 to 140 F. downto approximately 115 to 125 F., or a drop of approximately 15 F. Thethus cooled emulsion is then, subjected to the action of a pugmill orsimilar beater after treating the emulsion with about 0.02% to 0.05% byweight of an electrolyte such as potassium dichromate. The purpose ofthis treatment with the electrolyte is to thicken or fiocculate thecooled emulsion so that under the beating action of the pugmill, theparticles of dispersed bitumen will be further reduced in size. Thistreatment of the emulsion is preferably such as to reduce ,the

particle size of the emulsion to an average of about 7 microns. Thisgreatly reduced average particle size also contributes to the ease withwhich the kerosene may be incorporated in the emulsion without prematurebreaking thereof.

The emulsion with the reduced particle size is still comparatively thickdue not only to the fact that the water present must surround thegreatly increased amount of surface area of the increased number offiner particles, but also to the thickening effect of the electrolytepresent therein. In order therefore to thin out the emulsion of thereduced particle size and thereby facilitate the incorporation of thekerosene or other activating agent, the emulsion as discharged from thepugmill is then preferably cooled to a temperature of about 100 to 110F. and is then led into a second pugmill operating at a relatively highspeed, viz., of the order of 150 R. P. M. and the oxalic acid istrickled into the emulsion in this pugmill while the emulsion is beingagitated at a high speed. .The agitating action of the high speedpugmill as well as the introduction of the oxalic acid serves to greatlythin the emulsion of reduced particle size without requiring anysubstantial additional water.

It will .be appreciated that since the high speed The base emulsion asto thin the emulsion, these expedients may be used more or lessinterchangeably with one another, depending upon'the operatingconditions prevailing, which will determine the most economical mode ofbringing about the thinning of theemulsion. Furthermore where thethinning action is attained by the incorporation of a thinning agent,materials other than oxalic acid may be used for this purpose in lieu ofthe oxalic acid. After the emulsion with the reduced particle size hasbeen thus greatly thinned in the manner described, it may be transferredto a separate mixing tank where the kerosene or other activating agentis added while the material is being stirred in the mixing tank, thekerosene being preferably fed into this tank simultaneously with thefeeding of the emulsion thereinto. During this incorporation of thekerosene or similar activating agent into the emulsion, itis quiteessential that a comparatively low temperature be maintained and that,as already stated, the emulsion be of a thin consistency and have theparticles thereof in a state of subdivision of the order of magnitudespecified, in order to avoid inverting of the emulsion by the keroseneor other activating agent. With that in mind, it is desirable beforefeeding the emulsion into the final mixing tank, to run into this tankabout 50 to 100 gallons of water per 2000 gallons of finished product.The effect of this water introduced into the bottom of the tank beforeany of the emulsion is fed thereinto, is to greatly reduce thetemperature of the emulsion, namely from about 95 to 100 prevailing inthe second pugmill to about 80 F.; and also, to further thin theemulsion. v

The water in the bottom of the final mixing tank also prevents anymechanical friction during the mixing of the kerosene with the emulsion.The objective in this final step of the process is to incorporate thekerosene in the emulsion in the form of fine droplets of the keroseneuniformly dispersed in the aqueous phase of the emulsion. This result isattained by conducting this step of the process in the manner described,it having been found that by having the emulsion veryrthin and theasphalt particles in the emulsion very finely divided, any tendency forthe emulsion to break upon the addition of the kerosene can be avoided.This danger of breaking of the emulsion is further minimized by reasonof the fact that the additional quantities of water placed in the bottomof the mixing tank as aforesaid, prevents any substantial rubbingcontact between the kerosene and the dispersed asphalt particles, whichmight, by accumulating to a sufficient extent, cause the emulsion tobreak during the introduction of the kerosene.

Having thus described the invention and the advantages thereof, it willbe evident to those skilled in the art that numerous changes ormodifications may be made therein, without departing from its scope asdefined in the appended claims.

What I claim is:

l-. The method of uniting a layer of relatively impermeable fibroussound deadening or vibration damping material to the surface of animpervious metal panel or the like, which comprises interposing betweenthe said layer and the said surface a film of an aqueous emulsion of awaterproof substance, said emulsion containing an inverting agent tocause the emulsion to coalesce when 20 to 90% of its original watercontent still remains in the film, and subjecting the thus united sounddeadening or vibration damping layer and the metal panel or the like totemperatures above 212 F., whereby said film will hold said layeragainst displacement from said surface during conversion into steam ofsaid remaining Water content of the film.

2. The method as in claim 1 where the said I greatly in excess of themelting point of the said Waterproof substance.

mWIN O. GROSKOPF.

